Not to poke my retired nose in here
but maybe you could branch on major component(s) being worked on by the name of the component. There's also revision numbers, which are harder to comprehend for most. Or set milestones and branch that way, merging the final results back into the trunk when ready.
I see lots of people using Branching as a post-release tracking system too (ie., we release v1.0, branch it. release 1.5, branch it, etc). Not the text-book use, but it seems to work (Wordpress I believe does this).
As an aside, being away a while and coming back to seeing so much life here again - very exciting. Great work, guys.
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